Re: cross-device copying / USB improvements

if you mean that *the user* could use rsync instead of cp
in the first place - then you are right

but that was the whole point of my suggestion - to give a better user
experience:
IMHO the user should not have to know and install a tool like rsync
(nor to know mirror-copy) only to be able to transfer data reliably and
resumeable from one device to another... I mean, it's such a basic thing
that one tool (cp) should do it.

I don't agree. Each tool does its job. cp does copy. rsync syncs
files. Anyways, I wonder how do you wind up with a partial copy? Do
you ^C it? I can't imagine any other situation. I believe that less
than 0.0001% uses of cp are trying to resume a copy.